The invention concerns an arrangement of a cover strip for closing bores of a guide rail of a linear guide that are equipped with fixing screws, the cover strip being inserted into a longitudinal groove of the guide rail, an outer surface of the cover strip with respect to the guide rail being disposed in one plane with a running surface of the guide rail, the cover strip comprising two resilient retaining ledges that effect fixing and extend in longitudinal direction of the guide rail while being arranged within the longitudinal groove to bear against lateral groove walls of the guide rail that delimit the longitudinal groove.
Guide rails are used on machine tools and, being wear parts, they have to be replaced from time to time for which reason, they are often fixed on the machine frame by screws. It is known to close the bores of a guide rail containing fixing screws either by inserting a plug into the end section of each bore as disclosed, for example, in the documents DE 30 46 590 A1 and DE 93 16 349 U1, or the guide rail is provided with a groove-like recess aligned to the fixing bores, and a cover strip is fitted into this recess. Arrangements of this type are shown, for example, in the documents DD 237 805 A1 and EP 0 311 895 A1. The cover strip is often glued to the guide rail within the groove-like recess so that there is a danger of the glued joint coming loose.
In a linear guide arrangement known from the document DE 38 12 505 A1, a plastic plate or strip is inserted from one end of the guide rail into a longitudinal groove and positively retained therein by ribs. These ribs are integrally formed on the lateral surfaces of the strip and, within the longitudinal groove, they engage into appropriately recessed sections of the guide rail. A longitudinal groove of this type or a dovetail configuration for accommodating a trapezoidal strip can, of course, be made by grinding but since this necessitates very small tools, such a solution would become very expensive.
The document DE 195 24 810 A1 shows an arrangement of the initially cited type in which the cover strip is made up of an upper layer and a lower layer and the two retaining ledges are formed by bending over the long sides of the lower layer. Within the longitudinal groove, the upper layer of the cover strip bears against lateral contact surfaces of the guide rail that are obtained by milling of webs whose inclined portions are produced by pressure rolling and subsequent grinding so that their manufacturing is complex and cost-intensive. Besides this, there is no support for the central region of the cover strip on the guide rail within the longitudinal groove. Thus, there is a potential danger of deformation and vaulting of the cover strip which would detract from the sealing effect on its upper surface.
It is an object of the invention to improve the arrangement of the cover strip on the guide rail in its function and to make its manufacture more economic and cost effective.
This and other objects and advantages of the invention will become obvious from the following detailed description.
The invention achieves the above objects by the fact that the cover strip is supported through a flat inner surface on a flat support surface of the guide rail, which flat support surface delimits the longitudinal groove in inward direction, and two longitudinally extending recesses which lead to the formation of the resilient retaining ledges are made in the inner surface of the cover strip in regions of long sides of the guide rails.
Each lateral groove wall of the guide rail can comprise an undercut with a concave cross-section into which a bulge of the adjoining retaining ledge is snapped in. The bulge of the retaining ledge can merge into a V-shaped end region extending toward the guide rail.
The cover strip can be a metal part, for example, a rolled steel strip in which the retaining ledges are formed as a result of the recesses made therein. Such a strip has the advantage that it can be stocked and transported as a roll which can be unwound and cut to size as required for each particular linear guide.
The rolled cover strips of the invention are very economic to manufacture and can be made in any desired length, that is, as endless profiles. The locking of the cover strip in the guide rail is made possible by the appropriate configuration of the rail in the region of the longitudinal groove and by the strip contour. Through the embodiment of the cover strip of the invention, a one-piece seamless and smooth cover is obtained. All that is required for assembly is to press the rolled cover strip into the guide rail.
Due to the special geometry of the cover strip and the longitudinal groove, the cover strip is always in even contact with the support surface so that a deformation and bulging of the cover strip is not possible. This guarantees a long life of the seals of the linear guide which slide on the outer surface of the cover strip and the adjacent running surface of the guide rail during operation.
One example of embodiment of the invention is illustrated in the drawings and will be described more closely in the following in comparison to prior art arrangements and with reference to the drawings.